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901.
Summary A Modified-Melt-Powder-Melt-Growth (MMPMG) technique has been developed for the preparation of melt-textured Y-Ba−Cu−O pellets.
To test their performances, the samples were characterized with respect to their microstructure, pinning strength and interaction
force with permanent magnets. A superconducting magnetic bearing was built and integrated in a levitating flywheel system
for energy storage.
Paper presented at the “VII Congresso SATT?, Torino, 4–7 October 1994.
Under a Fondazione Confalonieri grant. 相似文献
902.
We make a thorough non-covariant analysis of the derivation of the equation of motion for a charged particle, including radiation reaction, by means of a simple model for the charge: a dumbbell. This model and our method to expand retarded quantities, based on complex-variable theory, allow us to avoid some of the usual approximations, so we can show several features of the radiation reaction problem. 相似文献
903.
Jean-Jacques Jutier Even Lemieux Robert E. Prud'homme 《Journal of Polymer Science.Polymer Physics》1988,26(6):1313-1329
The miscibility of polyester/nitrocellulose blends was investigated by differential scanning calorimetry and Fourier-transform infrared (FTIR) spectroscopy. Two nitrocelluloses (NC) derived from wood and having different nitrogen contents (12.62 and 13.42%) were used. On the basis of the glass transition temperature criterion, poly(?-caprolactone) (PCL), poly(valerolactone), poly(ethylene adipate), and poly(butylene adipate) are miscible with nitrocellulose, whereas poly(α-methyl α-propyl β-propiolactone) and poly(α-methyl β-proiolactone) are immiscible. The Tg versus composition curves of PCL/NC blends do not follow a monotone function but exhibit a singular point at a critical PCL volume fraction of 0.51 for NC-1342 and 0.45 for NC-1262 in agreement with Kovacs' theory. A shift of 17 cm-1 of the carbonyl stretching band was observed with PCL/NC blends and is taken as evidence for hydrogen bonding interaction between the PCL carbonyl group and NC hydroxyl group. The frequency difference between the free hydroxyl absorbance and the absorbances of the hydrogen-bonded species was found to be 85 cm-1 in pure NC and 125 cm-1 in PCL/NC blends; it indicates that the average strength of this interaction is stronger than the corresponding self-associated hydrogen bonding in pure NC. The presence of a dipole-dipole interaction between the nitrate-ester groups of NC and the carbonyl groups of the polyesters is reported. The relative strength of the hydrogen bonding and dipole-dipole interactions is discussed and correlated with polymer miscibility. 相似文献
904.
E. I. Timoshenko 《Mathematical Notes》1995,57(4):414-420
Translated from Matematicheskie Zametki, Vol. 47, No. 4, pp. 597–605, April, 1995. 相似文献
905.
906.
907.
908.
About 40 epoxide-amine network polymers with glass transition temperatures ranging from 0 to 232°C were investigated, about one-third being reported for the first time. The glass transition temperature Tgl of the corresponding linear copolymers was first calculated by use of an additivity law whose physical validity was carefully checked. Then the contribution of crosslink mers was determined, and various physical and empirical approaches of the effect of crosslinking on Tg were compared. The results gave evidence in favor of the DiMarzio approach. A predictive relationship based on these considerations is proposed. 相似文献
909.
Lahiouel R. Pierre J. Siaud E. Galera R. M. Besnus M. J. Kappler J. P. Murani A. P. 《Zeitschrift für Physik B Condensed Matter》1987,67(2):185-191
Magnetic properties, electrical resistivity, specific heat and magnetic excitations have been investigated in Heusler phases CeInAg2–xCux. The hybridization continuously increases from CeInAg2 (antiferromagnetic Kondo lattice) to CeInCu2 (heavy fermion compound). The specific heat coefficient for this last compound is found to reach 1.2 J/mole. K2 at 1.4 K, the Kondo temperature is 6 K and the Wilson ratio is close to 2. 相似文献
910.
Data about the existence of native HO? CH2? CH2? OH (MEG) in natural wines and champagne has led to delicate questions because of legal decisions already made to declare wine or champagne illegal for sale if the MEG concentrations found are above 10 mg/liter. Action has been taken because of the DEG (diethylene glycol) disaster in European wines of 1985…86. An incorrect legal decision was made due to the belief that MEG cannot be produced biochemically by grape vines. A further reason may be lack of correct data on native MEG trace concentrations, as a result of the special behavior of this diol. As first member of a homologous series whose higher members (C4) are normally found in all wines at quite high concentration levels, MEG shows extremely adsorptive behavior. The solution of the chromatographic problems is summarized in this paper. MEG concentrations in Riesling as example are in the range of 2 to 6 mg/liter and can easily be increased by biotechnological steps to a level of around 10 to 60 mg/liter. This is again due to the specific adsorptive behavior of MEG, which can be enriched on filter surfaces and displaced when the wine acidity changes with changing types. In order to control and guarantee the qualitative and quantitative results of MEG analyses we used a combination of Deans heart cutting on-line with Multi-Chromatography. It was easy to produce false data by many otherwise useful single column or two-dimensional separation processes, etc. 相似文献